- PV is a blistering skin disease that is triggered by an autoimmune response against desmoglein-3 (dsg3). This proposal investigates the cellular immune mechanisms involved in the production of pathogenic autoantibodies in PV. The research proposal tests the hypothesis that a restricted set of dsg3 T cell epitopes is essential in triggering an oligoclonal T cell response that promotes the production of pathogenic autoantibodies by dsg3-specific B cells. Identification and characterization of disease-specific T and B cells will provide valuable tools for defining the regulatory mechanisms involved in the PV autoimmune response. Specific Aim 1 focuses on developing and characterizing dsg3-specific B cells from PV patients. The immortalization of PV B cells will be accomplished by the use of EB virus or a retroviral vector which are available to the principal investigator. The structure and pathogenicity of antibodies produced by these B cells will then be analyzed. In Specific Aim 2, the principal investigator will define dsg3 epitopes involved in the activation of PV-specific T cells and determine whether a particular clonotype of T cell is crucial in promoting pathogenic anti-dsg3 antibody production in PV patients. The Preliminary Data show that the principal investigator and his colleagues have expressed the extracellular domain of dsg3 as a soluble recombinant glycopeptide (rdsg3) in the baculovirus system and have also expressed dsg3 bacterial fusion proteins that cover the entire dsg3 ectodomain. The principal investigator has already shown that rdsg3 is capable of stimulating PV T cell proliferation and has begun to develop and characterize T cell lines derived from the rdsg3-stimulated cultures. In Specific Aim 3, the principal investigator will utilize the molecular information obtained in the first two aims to generate peptide analogs designed to block the proliferation and effector functions of PV T cells. In Specific Aim 4, the principal investigator will focus on establishing an alternative active immunization animal model of PV. This model will overcome the major limitations inherent in the conventional passive transfer model of PV--such as the major limitation of not being able to investigate the cellular mechanisms regulating autoantibody production in a passive transfer type of animal model. The alternative model system proposed by the principal investigator involves active immunization of mice with recombinant forms of human or murine dsg3. In characterizing dsg3-specific T and B cells in PV and also establishing a new active immunization type of animal model of PV, the principal investigator believes that new and relevant information about the cellular mechanisms of autoantibody formation in PV will be revealed and will facilitate the development of novel therapeutic strategies to treat PV.